Due to several fire events that occurred in New York City and the difficulty of extinguishing flames on top of high-rise buildings, building codes have been revised in recent years to include detailed requirements for cooling tower fill combustibility. A quick internet search for “cooling tower fire events” will provide a few high-profile incidents that prompted the revisions to the code. Most often, the fires were ignited during maintenance and cleaning of the tower.
It can be difficult to understand the code requirements, so below, we have provided an interpretation of the codes and an explanation on why Brentwood’s family of stainless steel products may be the best choice for fire protection.*
Section 908 of The New York City Mechanical Code (Title 28, Chapter 8) covers requirements for new cooling equipment, including wet cooling towers. The requirements for new equipment are split into indoor and outdoor equipment, but it should be rare for a cooling tower to ever be considered “inside”. If it were, the fill and drift eliminators must be non-combustible materials, with no exceptions.
For cooling towers that are outside, section 908.3.2 requires non-combustible materials, but several exceptions are given that allow “limited combustible materials” for only the fill and drift eliminators. According to the definitions in the code, any Brentwood product with an ASTM E84 flame spread index (FSI) of 25 or less would qualify as a “limited combustible material.”
The code allows limited combustible material to be used for fill and drift eliminators if an automatic sprinkler system is provided in the cooling tower. This sprinkler system must meet all requirements in the NYC building code. If you don’t have an automatic sprinkler system, you can also use limited combustible materials for the fill and drift if all the following conditions are met:
- The tower is located on a Type 1A or Type 1B building, which is a building with the highest fire protection rating.
- The tower is at least 30 feet from windows and fresh air intakes.
- The tower is located more than 15 feet from the lot line.
- The tower is located more than 10 feet from a gas or oil furnace chimney, and more than 20 feet from any other type of chimney.
Given the limited roof space of most buildings in New York City, it can be difficult to meet all the conditions above and limits the options for future infrastructure changes. The choice for meeting the building code may come down to installing an automatic sprinkler system vs. using non-combustible fill. While it may seem more economical to install a sprinkler system than outfit a tower with stainless steel fill and drift, the total cost of ownership for Brentwood’s non-combustible products may be much lower.
An automatic sprinkler system requires testing and periodic inspection, and corrosion may reduce the life of some sprinkler components within the wet conditions of the tower. In the case of a cooling tower replacement, it may be a large infrastructure investment to add additional capacity to the water supply and achieve the required water pressure at the cooling tower sprinkler heads. Replacement costs of the fill and drift eliminators must also be considered; standard PVC fill will most likely need to be budgeted for replacement every 10 years. And in the unfortunate event of a fire, some damage to components is likely to occur before the fire is extinguished.
In contrast, Brentwood’s stainless steel products require no maintenance and will last the lifetime of the tower, avoiding the capital cost and maintenance overhead of an automatic sprinkler system. Since the metallic components don’t provide any fuel for combustion, it is very unlikely a fire event will ever originate from the tower. The stainless steel components are extremely durable and allow for thorough cleaning using a pressure washer, steam cleaning, and chemicals.
Since louvers are not specifically called out in the code, an enforcement officer may indicate that louvers must always be non-combustible material to meet the requirements. Since louvers slightly overhang the cell walls and they are below the fill, an automatic sprinkler system in the plenum of the tower will be very ineffective in extinguishing louvers. Brentwood’s metallic inlet louvers are a low pressure drop, non-combustible replacement and are available in a variety of sizes to fit all packaged towers.
With the entire family of metallic products, Brentwood can assist contractors in New York City and other metropolitan areas in achieving building code compliance for most counterflow and crossflow tower designs.
*The code descriptions above are not to be considered legal advice, and an expert should be consulted for compliance.